1. Field of the Invention
The present invention relates to an endoscope apparatus, and in particular to an endoscope apparatus capable of displaying a blood vessel inside a subject.
2. Description of the Related Art
Conventionally, various kinds of minimally invasive examinations and operations using an endoscope have been performed in a medical field. A surgeon can insert an endoscope into a body cavity, observe a subject which has been image-picked up by an image pickup apparatus provided at a distal end portion of an endoscope insertion section, and treats a lesioned part using a treatment instrument inserted in a treatment instrument channel as necessary. An operation using an endoscope is advantageous in that a bodily burden on a patient is not heavy because an abdominal operation is not performed.
An endoscope apparatus is configured including an endoscope, an image processing apparatus connected to the endoscope and an observation monitor. An image of a legion is picked up by an image pickup device provided at a distal end portion of an endoscope insertion section, and the image is displayed on the monitor. The surgeon can make a diagnosis or perform necessary treatment, looking at the image displayed on the monitor.
Some endoscope apparatuses are capable of not only performing normal light observation using a white color light but also performing special light observation using a special light such as an infrared light in order to observe an internal blood vessel.
In the case of an infrared endoscope apparatus, for example, indocyanine green (ICG) having an absorption peak characteristic in a near infrared light near a wavelength of 805 nm is injected into a patient's blood as medicine. Then, infrared lights near wavelengths of 805 nm and 930 nm are radiated to the subject from a light source device in a time division manner. A signal of a subject image picked up by a CCD is inputted to a processor of the infrared endoscope apparatus. As for such an infrared endoscope apparatus, an apparatus is proposed in which the processor allocates an image near the wavelength of 805 nm to a green signal (G) and allocates an image near the wavelength of 930 nm to a blue signal (B), and outputs the images to a monitor as disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 2000-41942. Since the image of the infrared light near the image of 805 nm which is well-absorbed by the ICG is allocated to green, the surgeon can observe an infrared image during administration of ICG with high contrast.